Windows/Mac/Linux (Firefox): The Google Doc Download Greasemonkey script adds a download link to the main Docs and Spreadsheets page that gives you quick access to download your docs in whatever format you want.

Clicking the download link lists all of your files with direct links to downloads. The script is streamlined for use with previously mentioned DownThemAll so that you can quickly suck down backups of all of your Google Doc files, a process that's much more of a pain than it should be as-is. Google Doc Download is free, requires Greasemonkey and Firefox.